Graciela De Lara-Isassi’s research while affiliated with Metropolitan Autonomous University and other places

Antecedentes: Las algas son una fuente potencial de compuestos naturales con actividad biológica diversa. En particular, se ha reportado que las algas pueden contener compuestos hipoglucemiantes e hipolipidémicos, por lo que representan una alternativa para el control de la diabetes mellitus, enfermedad con los más altos índices de prevalencia y mortalidad en México. Objetivos: Determinar el efecto hipoglucémico e hipolipidémico de los extractos de dos especies algales (Caulerpa sertularioides y Spyridia filamentosa) a través de un estudio subcrónico en un modelo murino de diabetes experimental. Métodos: Los extractos se administraron por vía oral durante 30 días a ratones con diabetes experimental (50 mg/kg/día), usando solución salina isotónica y glibenclamida (5 mg/kg/día) como controles. Al final de los tratamientos se midió glucosa, colesterol total, triglicéridos, aspartato aminotransferasa y alanina aminotransferasa. Resultados: Se observó que las dos especies algales reducen de manera significativa la glucemia, aunque también producen alteraciones en los lípidos sanguíneos. Los niveles de transaminasas permanecieron sin cambios, indicando ausencia de hepatotoxicidad. Conclusiones: Ambas especies representan una alternativa como fuente de nuevos fármacos para el control de la diabetes mellitus.

Seventy-three species of macroalgae from the Mexican Pacific, Atlantic and Caribbean coast were screened for ichtyotoxic activity. Ethanolic, acetonic and aqueous extracts were prepared and tested against the fish Carassius auratus. The extracts were classified on the basis of their effects as: toxic if the fish died in two hours or less; moderately toxic, if the organism behaved abnormally but death did notoccur, and non-toxic if the fish did not display any change. 79% species were ichtyotoxic to some degree. Extracts of 39 species were toxic, with at least one extract with lethal effects, 19 were moderately toxic and 15 species were non-toxic. Only the extracts ofDictyota bartayresiana, Dictyota cervicornis,Lobophora variegata, Bryothamnion triquetrum and Laurencia obtusa were toxic in all three solvents. The acetone and ethanol extracts were more active, and therefore are more suitable for extraction of toxic substances.

Zooplankton composition and abundance study from Chantuto and Panzacola estuarine systems, Chiapas, in dry (May of 1997) and rainy seasons (July of 1997) is presented. Zooplankton samples were taken using a standard net with 30 cm in mouth diameter and a mesh opening of 250 µm. Temperature, salinity, pH, and dissolved oxygen were measured in the water. The differences of the physical-chemical parameters among the dry and rainy seasons were found in the salinity averages, 23 to 13 psu respectively and in the percentages of oxygen saturation , 90 to 50 % respectively. Twenty species of zooplankton were identified, a genus of the Phylum Chaetognatha, 11 larval forms and several non identified species of fish eggs. In the dry season the copepods Canthocalanus pauper and Pseudodiaptomus culebrensis were dominant while in rainy season the dominant species was Oithona nana. None of the mentioned copepods had been considered before as dominants in Mexican estuarine systems.

The coagulation disorders have increased in the last decades and no new substances had been discovered that could regulate this illness. This fact makes the discovery of new anticoagulant substances a priority issue in research. Forty nine seaweed species collected off shore of several localities of Gulf of Mexico and Mexican Caribbean sea were screened in order to detect anticoagulant activity in both intrinsic and extrinsic pathways of clot formation. Standardized plasma coagulation tests (thrombin and prothrombin time) were used. Heparin, a sulphated glycosaminoglycan wide used in oral anticoagulant therapy, was used as reference in both proofs. The results showed that four species presented potent anticoagulant activity same as heparin in the two pathways: Anadyomene stellata, Caulerpa cupressoides (Chlorophyta), Lobophora variegata (Phaeophyta) and Liagora farinosa (Rhodophyta). Caulerpa paspaloides (Chlorophyta) was active only in the thrombin time test. Other seven species presented a slightly anticoagulant activity. We considered that algal extracts have substances capable of inhibit clot formation in the last steps of the coagulation cascade. The extracts could act preventing the conversion of prothrombin to thrombin, also they could act stopping the transformation of fibrinogen to convert it to fibrin o even in the polymerization of this last molecule. This is the first report of anticoagulant activity in Anadyomene stellata, Lobophora variegata and Liagora farinosa. We can concluded that these species can be considered as potentially alternative source of anticoagulant molecules. Palabras clave: Anticoagulant activity, marine algae, Gulf of Mexico, heparin RESUMEN

A study on ecological records of planktonic copepods from The Ventosa Bay, Oaxaca, Mexico is presented. Five species were identified: Labidocera acuta, L. lubbockii, Pontella agassizi, P. tenuiremis and Pontellina plumata. The most abundant species was L. acuta and their copepodite stages conforming the 95.7% of Pontellids, followed by L. lubbockii 4.09%; other species were less than one percent. The reproductive success of L. acuta is probably favored by its resistance to the changes in temperature and salinity, because of it is an eurytherme and euryhaline organism. Total density of this family was between 18 and 472 copepods/100 m3 in 1987 and 1988. Nevertheless in 1992 and 1993 the density was between 490 to 123,030 copepods/100 m3. This copepod density increment could be related local phenomenon (upwelling) at the beginning and end of the year.

A study on ecological records of planktonic copepods from The Ventosa Bay, Oaxaca, Mexico is pre- sented. Five species were identified: Labidocera acuta, L. lubbockii, Pontella agassizi, P. tenuiremis and Pontellina plumata. The most abundant species was L. acuta and their copepodite stages conforming the 95.7% of Pontellids, followed by L. lubbockii 4.09%; other species were less than one percent. The reproductive suc- cess of L. acuta is probably favored by its resistance to the changes in temperature and salinity, because of it is an eurytherme and euryhaline organism. Total density of this family was between 18 and 472 copepods/100 m3 in 1987 and 1988. Nevertheless in 1992 and 1993 the density was between 490 to 123 030 copepods/100 m3. This copepod density increment could be related local phenomenon (upwelling) at the beginning and end of the year.

A phylogenetic model for the selection of commercial resources using the cladistic method is proposed. The group selected as an example was the marine agarophyte red algal genus Gracilaria Greville. We suggest the use of the cladistic principle of evolutionary transformational series in order to test the quality of agars instead of the assay-herror traditional method that consumes time and budget. If we asume that the “good quality of agar” in extant taxa is a sinapomorphic character (but not a reliable taxonomic one), then taxa included in the same monophiletic clade in which the species with “good quality of agar” are, has a high evolutionary posibility to share that character. In order to do this we have to incorporate to the set of available specific characters, those of the taxa actually used as a agar source but not present in the area under scope. A complete set of the basic cladistic data required for run the most popular program currently in use (PAUP) are provided. We applied the model to the Mexican Atlantic species and found that, using Gracilaria chilensis and G. cornea as “indicator taxa,” and found Mexican populations of G. crassissima, G. caudata, G. cervicornis and Gracilariopsis lemaneiformis are candidates for a study of yield and agar properties.

In order to separate two strains of tilapia Oreochromis) of O. niloticus (red and stirling strains) and rocky mountain hybrid (O. aureus x O. niloticus) the lectin giraffine isolated from Codium giraffa (Chlorophyta) was used. Fish blood was obtained by cardiac puncture and prepared as a 2 % suspension in phosphate buffer 100 mM, pH 7.2. At all cases, the lectin giraffine agglutinated the fish blood. The statistical analysis of agglutination results showed significantly differences (p ≤ 0.05) at single classification analysis of variance. Multiple comparisons among means SNK test shows overlapping between red and stirling strains, and could separate the hybrid rocky mountain from this group. We can concluded that giraffine can be used as an easy and cheap test for grouping these fishes. This test can aid the researcher to follow correctly the progeny of this fishes, commercially valuable as a food in Mexico.

The presence or absence of secondary metabolites in algae has been long discussed. There are several hypotheses to explain the synthesis of secondary metabolites in algae as a response to herbivory pressure, competence or predation. In this work we made a screening test of chlorophyte and rhodophyte species collected in different sites of the Caribbean sea in order to test them for agglutinins. The extracts were prepared in a phosphate buffer solution 100-mM, pH 7.2 and filtered using 0.22 μm Millipore filters. Agglutination tests were done in microtiter-plates using formalinized rabbit and human A, O, B erythrocytes. Agglutination titer was recorded and expressed as the reciprocal of the highest dilution showing positive results. A total of 31 samples were analyzed; seven Chlorophyta species and 11 Rhodophyta showed agglutinating activity. The species that showed activity variation included the chlorophytes, Caulerpa cupressoides, Caulerpa paspaloides, Halimeda opuntia and Penicillus capitatus and the rhodophytes, Chondria litoralis, Digenea simplex, Gracilaria cornea and Laurencia obtusa. The agglutinating activity of Liagora farinosa is reported for the first time. This research indicates that ecological pressures are an important factor in seaweeds agglutinins synthesis.